#!/bin/sh

function s1_read_last_two_bytes_of_a_mbr_backup_file() {
    local file_path=$1 
    local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n')
    if [ "$last_bytes" = "55aa" ];then
        echo "YES"
    else
        echo "NO"
    fi
}

function s2_read_mbr_partition_table_info() {
    echo -n `echo "ibase=16; 800" | bc`
    echo -n ' '
    local mbr_backup_file=$1
    for i in {0..3}; do
        local offset=$((446 + i * 16))
        local partition_entry=$(od -j $offset -N 16 -t x1 -An "$mbr_backup_file" | tr -d ' \n')
        local partition_type=$(echo $partition_entry | cut -c 9-10)
        if [ "$partition_type" != "00" ]; then
            local start_sector_hex=$(echo $partition_entry | cut -c 17-24 | tr '[:lower:]' '[:upper:]')
            local start_sector=$(echo "ibase=16;$start_sector_hex" | bc)
            local end_sector_size_hex=$(echo $partition_entry | cut -c 33-40 | tr '[:lower:]' '[:upper:]')
            local end_sector_size=$(echo "ibase=16;$end_sector_size_hex" | bc)
            local end_sector=$((start_sector + end_sector_size - 1))
                if [ $i -eq 0 ];then
                    echo -n "$end_sector "
                    echo -n "$start_sector "
                else
                    echo -n "$end_sector"
                fi
        fi
    done
}

function s3_parse_partition_info(){
    fdisk_output=$(cat)
    disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
    disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
    physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
    first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}')
    first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
    first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
    echo "disk size in bytes:$disk_size_bytes"
    echo "disk size in sectors:$disk_size_sectors"
    echo "physical sector size in bytes:$physical_sector_size"
    echo "first partition start sector id:$first_partition_start_sector"
    echo "first partition end sector id:$first_partition_end_sector"
    echo "first partition type:$first_partition_type"
}

function s4_run_passwd_as_plain_user_and_get_status() {
    oversleeping_path=$(which oversleeping)
    chown root "$oversleeping_path"
    chmod 755 "$oversleeping_path"
    $oversleeping_path &
    ps -o uid,euid,ruid -C 'oversleeping' | awk 'NR>1 {print $1","$2","$3}'
}

function s5_add_a_scheduled_task() {
    (crontab -l 2>/dev/null; echo "*/5 * * * * echo \$(date +'%Y%m%d_%H%M%S') >> \$HOME/test_crontab") | crontab
}